Scalable video coding is envisaged for wireless transmission of High Definition television signals (WirelessHD), in particular for the purpose of invisibly connecting a wall-mounted HDTV flat screen monitor to an external HDTV signal source. Scalable means that a bitstream produced by the encoder can be truncated.
A prior art method of obtaining a scalable bitstream is disclosed in U.S. Pat. No. 6,462,681. The prior art comprises dividing each image in image blocks, transform encoding each image block in corresponding block bitstreams, and forming the scalable bitstream by iteratively scanning the blockstreams, including in each scan a part of the data in the block bitstreams.
In experimental evaluations in the context of WirelessHD, the inventors found that an improvement of the compression performance was desired for certain computer-graphics content. For WirelessHD, both natural image content and graphics content should be supported. The prior art method is designed for natural image content and is not specifically optimized for graphics content.